Packaging laminate, creasing roller,and a layer for use as a packaging laminate

ABSTRACT

The present disclosure describes a packaging laminate where at least one of the material layers included in the laminate includes magnetisable particles. Further, a roller is disclosed which includes means for applying crease line patterns on a packaging laminate and means for applying magnetic fields for magnetising magnetisable particles in the packaging laminate. Finally, a layer is also described for use for a packaging laminate, the layer including magnetisable particles.

TECHNICAL FIELD

The present invention relates to a packaging laminate. The presentinvention further relates to a creasing roller including means forapplying crease line patterns on a packaging laminate, as well as to alayer for use for a packaging laminate.

BACKGROUND ART

Within, for example, the printing and packaging industries, it is commonpractice to control working operations on a continuous material web byproviding guide markings by means of printing on the web, these guidemarkings being sensed by photocells or other optical devices. Thesemarkings or control markings are often printed in a colour tone whichmakes a clear contrast with its surroundings, preferably black, and isapplied on such panels or areas of the material web where no otherprinted markings or patterns occur. The markings may also be provided bymeans of magnetically sensible material or with the aid of mechanicallysensible markings such as, for example, holes, crease lines or slots.

These guide markings are employed, for example, in the printing ofmulti-colour print, to adapt the position of the patterns printed withdifferent colours to one another so that the different colour patternswill lie exactly superposed on one another. Another similar field of useis when the intention is, on a previously ready printed material web, toadd print at a predetermined place in the print pattern, for example abest before date or the like or when the intention is to provide aprinted pattern and a crease line pattern which facilitate fold forming,in register with each other.

Further fields of use are, for example, in those cases where theintention is, in a filling machine or the like, to advance a packagingmaterial web an exact pattern length in order, on the one hand, to havethe printed pattern in the same position on all packages, and, on theother hand, to cause the above mentioned crease line pattern to registerwith the forming devices of the filling machine so that the folding ofthe material takes place along the crease lines which are predeterminedin position.

One example of such a guide marking is described in EP-A-131 241. Onedrawback inherent in this type of guide marking is that the markingtakes up a certain area, which cannot then be provided with decorativeartwork. Another drawback is that mechanical action runs the risk ofscratching the mark, with the result that the detector intended for thepurpose does not correctly register the guide marking. A further problemwhich may arise in the employment of the above-mentioned type of guidemarking is that the guide marking is used for controlling the creasingmachine and that the guide marking is then also used for controlling thefilling machine. This implies that any possible tolerance errors in thepositioning of the crease line pattern in relation to the guide markingand on the detection and forming by the filling machine may, in theworst case scenario, be added to one another, which could result in thefilling machine attempting to fold the packaging material at theincorrect place in relation to the crease line pattern. Theabove-outlined problems are minimised according to current technology bymeans of finely tuned manufacturing machines and filling machines and bymeans of caution in the handling of the packaging material.

In this context, mention should also be made of EP-A-317 879 whichbriefly describes the employment of a magnetic guide marking in the formof magnetic strips placed on the packaging material. The publicationrelates to the design of the magnetic detector and is totally silent asto the design and construction of the magnetic guide marking. Themagnetic strip placed on the packaging material is, precisely like theoptically detectable guide marking, associated with problems in respectof tolerance errors in positioning and in subsequent processingoperations of the packaging material. In addition, it may also besubjected to scratching. Moreover, there are numerous magnetic sourcesof disruption in a filling machine of conventional type, which impedes acorrect detection of the position of the packaging material in thefilling machine. The latter problem has been addressed in thelast-mentioned publication in that the detector has been given aspecific design.

SUMMARY OF THE INVENTION

One object of the present invention is thus to realise an alternativesolution to the above-mentioned functioning of a guide marking. Afurther object of the present invention is to formulate the alternativesolution in such a manner that the inherent, above outlined drawbacks inthe prior art technology are obviated or that their effects on functionare at least reduced.

The above-outlined objects have been attained according to the presentinvention in that a packaging material of the type described by way ofintroduction has been given the characterising feature that at least oneof the material layers included in the laminate comprises magnetisableparticles.

By employing a layer with magnetisable particles, it is possible tomagnetically read off a guide marking even if this is not locatedoutermost, in other words it is possible to print decorative artwork onthe entire surface of the packaging container without needing to leaveany surface free for the guide marking. Moreover, the risk is reducedthat the marking be damaged by external mechanical effects. Since,according to the present invention, the formation of the decorativeartwork of the package has thus been separated from the formation of theinformation-carrying guide marking, it is further conceivable to employthe total surface of the packaging container as an information carrier,which entails that the packaging laminate and the package may beprovided with considerably more information than in prior art systems.

A further advantage which is afforded is that it is relatively simple tointegrate the production stage of providing the packaging laminate withthe crease line pattern with the production stage of magnetising theparticles. If it is chosen to utilise this advantage, it is possible toeliminate error tolerances between the guide marking and the creaselines, which entails that it is the settings of the filling machinewhich are determinative of the tolerances between the positioning of theguide marking and the actual forming of the packages.

The intended magnetisable particles retain their magnetic charge(magnetic remanence) even when they are no longer influenced by themagnetic field. The time interval which is relevant to consider for theparticles to be deemed to be permanently magnetisable (residualmagnetism for a sufficiently long time) naturally varies depending uponthe intended application. If the information which is stored by means ofthe particles is intended for controlling the filling machine, theinformation must have sufficiently good quality during the time it takesto transport and store the material until such time as it is employed inthe filling machine. If the intention is to provide information which isemployed by the retail outlet which sells the package, the relevant timelimit is consequentially extended. It is further conceivable that therelevant time limit is further extended if the information which ismagnetically stored is also intended to be employed in connection withrecycling of the packages or the like. The charge of the magnetisableparticles may be modified in that a new magnetic field is applied. Thus,it is, for example, conceivable that the filling machine reads off theoriginal information in order to control the formation operationcorrectly, whereafter the machine writes over with new information inrespect of product batch, product type, packing date or the like whichis intended to be used by the retail outlet or for tracing the package.

Preferred embodiments of the present invention will be apparent from theappended subclaims.

According to one preferred embodiment, the packaging laminate comprisesa layer with a basic matrix of plastic, the above mentioned magnetisableparticles being admixed in the basic matrix. In terms of productionengineering, this is a preferred embodiment, since the methods which areemployed for manufacturing plastic layers are suitable for admixingparticles into the plastic matrix.

According to yet a further preferred embodiment, the above mentionedbasic matrix is a thermoplastic, preferably a polyolefin plastic.Thermoplastics, and in particular polyolefin plastics, are suitable touse in packaging laminates and are moreover suitable for admixing ofparticles from the point of view of production engineering.

Advantageously, the above mentioned particles are metallic, since theypossess superior magnetic properties (they are relatively easy tomagnetise and display a satisfactory magnetic remanence).

The above objects have further been attained according to the presentinvention by means of a roller of the type described by way ofintroduction which has been given the characterising feature that itfurther includes means for applying magnetic fields for magnetisingmagnetisable particles in the packaging laminate.

By applying the crease line pattern and the magnetic guide marking usingone and the same roller, it has been possible to totally eliminate errorsources which otherwise occur on reading off of the guide marking in theconventional crease roller. By employing one and the same roller, it isonly manufacturing tolerances, if any, for the roller proper which giverise to an error. The packaging laminate according to the presentinvention with magnetisable particles makes it possible, in a relativelysimple manner, to integrate the creasing with the application of themagnetic guide marking. Combining printing with creasing is considerablymore difficult, since the printing requires a smooth roller in abutmentwith the packaging material while the creasing requires a roller withprojecting portions.

The above-outlined objects have further been attained according to thepresent invention by means of a layer for use for a packaging laminate,the layer having been given the characterising feature that it includesmagnetisable particles. By prefabricating a separate layer withmagnetisable particles, it is possible to optimise the productionprocess for this step in principle independently of the manufacture ofthe finished packaging laminate. Since modifications in laminationplants require costly capital investments, it is desirable if it bepossible to utilise the present invention in conventional laminationplants without major retroconstruction being required. Prefabricating alayer which is subsequently laminated together with remaining layers inthe packaging laminate is one method of avoiding excessively largeretroconstruction of the lamination process. Such a separate layer mayalso be employed for various types of labels. For examples labels forcans or so-called shrink on labels for various types of bottles.

The above-outlined objects have further been attained by means of anapparatus for carrying out a working operation on a laminate, theapparatus including means for carrying out the above mentioned workingoperation, and the apparatus further including means for applying amagnetic field for magnetising magnetisable particles in the laminate.By carrying out the working operation and applying the magnetic guidemarking or other information using one and the same item of equipment,it has been possible to completely eliminate the error source whichotherwise occurs when reading off the guide marking in conventionalsequential working operations. By employing one and the same item ofequipment, it is only manufacturing tolerances, if any, for theequipment which give an error. The packaging laminate according to thepresent invention with magnetisable particles makes it possible, in arelatively simple manner, to integrate different working operations withthe application of the magnetic guide marking or other information.Examples of such integrated working operations may be punching ofsemi-manufactured plastic bags at the same time as the punch carriesmagnetic devices for applying a magnetic marking in register with thepunching operation. Other working operations where it might beappropriate to apply the magnetic information simultaneously as theoperation is carried out are, for example, the welding of joints insemi-manufactured plastic bags, printing of various types of laminates,or other processing operations such as embossing, perforation or thelike. The combination between the magnetisation and the processingoperations can, of course, be carried out in systems with rollers, butalso other systems which, for example, employ flat plates for realisingwelding, punching, printing or other similar working operations.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detailhereinbelow, with reference to the accompanying schematic Drawingswhich, for purposes of exemplification, show currently preferredembodiments of the present invention. In the accompanying Drawings:

FIG. 1 shows a laminate structure for a rigid, fibre based packageadapted for refrigerated distribution;

FIG. 2 shows a laminate structure for a rigid, fibre based packageadapted for non-refrigerated distribution, a so-called aseptic package;

FIG. 3 shows a laminate structure for a bag-shaped package adapted forrefrigerated distribution;

FIG. 4 shows a laminate structure for a bag-shaped package adapted fornon-refrigerated distribution;

FIG. 5 shows a roller for creasing and magnetisation of a packaginglaminate;

FIG. 6 shows a laminate structure for a rigid, fibre-based packageadapted for non-refrigerated distribution; and

FIG. 7 shows a laminate structure for a bag-shaped package adapted forrefrigerated distribution.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As is apparent from FIG. 1, the packaging laminate comprises, accordingto a first embodiment, counting from that side which is intended toconstitute the outside of a finished package, a sealing layer 1, forexample of polyethylene plastic (PE), an information layer 2 of mineralfilled thermoplastic (for example a polyolefin plastic) with admixedmagnetisable particles, a lamination layer 3 of, for example, PE, a corelayer 4 of a fibre-based material, as well as a sealing layer 5 of, forexample, PE. This packaging laminate is adapted for refrigerateddistribution.

One example of a suitable mineral-filled polyolefin layer 2 comprises abasic matrix of polyolefin with inorganic mineral particles admixed inthe basic matrix in a quantity of from 5 to 85% of the total weight ofthe mineral-filled polyolefin layer.

Examples of usable inorganic mineral particles are dolomite, talcum,chalk, mica, limestone, marble, kaolin and wollastonite. Preferably, theinorganic mineral particles are a mixture of dolomite- and talcumparticles in which the quantity of dolomite particles is between 70 and90% and the quantity of talcum particles is between 10 and 30%,calculated on the weight of the mixture.

Preferably, the basic matrix of the mineral-filled polyolefin layerconsists of a propylene-based polyolefin, such as, for example, apropylene homopolymer or a copolymer of propylene and ethylene and/orother alkylene. An example of a propylene-based polyolefin could bepropylene homopolymer with an ASTM melt index of under 10 (2.16 kg; 230°C.) or a copolymer of propylene and ethylene and/or other alkylene withan ASTM melt index of 0.5-5 (2.16 kg; 230° C.).

As is apparent from FIG. 2, the packaging laminate comprises, accordingto a second embodiment, the same layers as in the first embodiment, aswell as a lamination layer 6 of, for example, PE and a barrier layer 7of, for example, aluminium foil between the core layer 4 and theinnermost sealing layer 5. The lamination layer 6 is located between thebarrier layer 7 and the core layer 4. This packaging laminate is adaptedfor non-refrigerated distribution.

Both of these packaging laminates are intended to be formed into rigidpackages possessing well-defined configurations. For example, rightparallelepipedic packages may be produced from these two packaginglaminates. Two laminate structures for so-called bags will be describedbelow.

According to a third embodiment, the packaging laminate comprises, as isapparent from FIG. 3 and seen from the side which is intended toconstitute the outside of a finished package, a sealing layer 1 of, forexample, PE, an integrated information and core layer 2 ofmineral-filled thermoplastic with admixed magnetisable particles, aswell as an inner sealing layer 5 of, for example, PE. This packaginglaminate is adapted for refrigerated distribution.

The integrated core layer 2 is preferably of the same type as wasdescribed in connection with the first embodiment, i.e. a mineral-filledpolyolefin layer.

As is apparent from FIG. 4, the packaging laminate comprises, accordingto a fourth embodiment, the same layers as in the third embodiment, aswell as a lamination layer 6 of, for example, PE and a barrier layer 7of, for example, aluminium foil between the core layer 2 and theinnermost sealing layer 5. The lamination layer 6 is located between thebarrier layer 7 and the core layer 2. This packaging laminate is adaptedfor non-refrigerated distribution.

Examples of metallic materials which may be employed for themagnetisable particles are chromium oxide, iron oxide, titanium,manganese or mixtures thereof. According to one example, use is made ofsubstantially spherical particles having a diameter of approximately 0.5μm. Experiments have proved that but limited quantities of magnetisableparticles are needed. It has also proved that the requisite admixingdegree reduces with the thickness of the particle-carrying layer. Therequisite admixing degree is also effected by the number of sources ofdisturbance which exist around the site where the information is to beread-off. Further, the requisite quantity of particles is alsoinfluenced by the distance at which it is to be possible to read theinformation, i.e. if the reading device can abut against the material orif there is an air gap or some other material layer between theinformation layer and the reading device. Trials with simple equipmenthave shown that a plastic film containing approximately 0.1 weightpercent of magnetite can be read without difficulty at a distancecorresponding to a paper layer when the film has a thickness of approx.50 μm. Theses trials have moreover been carried out in a conventionalfilling machine where the information has been employed to realiseguiding of the web. With corresponding simple equipment, it is possibleto reduce the level to 0.01 weight percent if the measurement is carriedout outside the filling machine. For a plastic bottle with a ten timesas thick layer, approximately a tenth of this admixing level can beemployed. Moreover, the quantity may be reduced if the reading-offoperation may be carried out directly adjacent the layer. If, moreover,it is possible to eliminate sources of disturbance or compensate forknown sources of disturbance, it is possible to reduce the quantity ofparticles even further. In addition, the quantity of particles may befurther reduced for applications where the design and construction cansupport a higher equipment cost, i.e. in those cases where it ispossible to employ the same type of reader head as is disposed in a harddisk for a computer. Under these conditions, it is possible to employadmixing quantities down to approximately 1 ppm (parts per million) andnevertheless obtain a detectable and technically usable informationquantity.

The upper limit in respect of the quantity of admixed magnetic particlesis determined int. al. by how much that can be mixed into the plasticwithout its other properties (in addition to magnetic behaviour) beingchanged excessively. For example, difficulties may arise with homogenousadmixture or excessively powerful blackening of the material. Trialshave demonstrated that admixtures of 1 weight percent and 10 weightpercent do not influence the admixture to any major extent. There arealso other similar particles which are mixed into plastics for otherpurposes which may be admixed in quantities of up towards 90 weightpercent without the admixture being disturbed to too great an extent.However, in certain cases blackening is powerful at 1 weight percent andexcessively powerful at 10 weight percent.

A method of manufacturing the plastic with admixed magnetic particles isso-called compounding in which the thermoplastic is molten and mixedwith minerals and additives. The magnetisable particles may be suppliedto the material during the compounding stage.

As is apparent from FIG. 5, the technique according to the presentinvention is suitable for simultaneous creasing and magnetisation of themagnetisable particles. The creasing roller 11 comprises a number ofcrease line pattern defining projections 12 which are disposed to creasethe packaging laminate 10. The roller further includes permanent orelectromagnets 13 which are disposed locally to magnetise particles inthe by-passing packaging laminate 10. The electromagnets 13 and theprojections 12 accompany the roller 11 in its rotation and will, thus,be positioned in relation to one another with an extremely high degreeof accuracy.

According to a fifth embodiment, the packaging laminate includes, as isapparent from FIG. 6, from that side which is intended to constitute theoutside of a finished package, a sealing layer 1 of, for example, PE, acore layer 4 of, for example, fibre-based material such as paper, anintegrated information layer 2 of mineral-filled thermoplastic withadmixed magnetisable particles, as well as an inner sealing layer 5 of,for example, PE. Moreover, between the inner sealing layer 5 and theinformation layer 2, the laminate is provided with a barrier layer 7,for example of aluminium. This packaging laminate is adapted fornon-refrigerated distribution. According to an alternative embodiment,the packaging laminate includes the above-mentioned layers without thebarrier layer 7. Such a packaging laminate is adapted for refrigerateddistribution.

According to a sixth embodiment, the packaging laminate includes, as isapparent from FIG. 7, from that side which is intended to constitute theoutside of a finished package, a sealing layer 1, for example of PE, acore layer 8 of mineral-filled polyolefin, an information layer 2 ofmineral-filled thermoplastic with admixed magnetisable particles, aswell as an inner sealing layer 5 of, for example, PE.

It will be realised that numerous modifications of the embodiments ofthe present invention described herein are possible without departingfrom the scope of the present invention as this is defined in theappended Claims.

For example, the PE film may be carrier of the magnetisable particles.In such instance, the present invention may be employed in connectionwith conventional packaging laminates which are employed today forfibre-based packages both for refrigerated and for non-refrigerateddistribution.

Further, use may be made of other plastics, such as polyester (forexample PET), or PA, or a fibre-based layer (e.g. paper layer) ascarriers of the magnetic particles. With plastics such as PET or PA, theadvantage will be afforded that, in certain cases, it is possible to addthe magnetisable particles already in the polymerisation (in situ), inother words the compounding stage is obviated.

1. A packaging laminate, wherein at least one of the material layersincluded in the laminate comprises magnetisable particles.
 2. Thepackaging laminate as claimed in claim 1, which includes a layer with abasic matrix of plastic, said magnetisable particles being admixed insaid basic matrix.
 3. The packaging laminate as claimed in claim 2,wherein said basic matrix is a thermoplastic, preferably a polyolefinplastic.
 4. The packaging laminate as claimed in claim 1, wherein saidparticles are metallic.
 5. The packaging laminate as claimed in claim 1,wherein said particles comprise at least 0.0001 weight percent of thelayer which includes magnetisable particles.
 6. A roller including meansfor applying crease line patterns to a packaging laminate, wherein itfurther includes means for applying magnetic fields for magnetisingmagnetisable particles in the packaging laminate.
 7. A layer for use fora packaging laminate, wherein it includes magnetisable particles.
 8. Alayer for use for a label for a package, wherein it includesmagnetisable particles.
 9. An apparatus for carrying out a workingoperation on a laminate, comprising means for carrying out said workingoperation, wherein the apparatus further includes means for applying amagnetic field for magnetising magnetisable particles in the laminate.